All our perceptions, sensations, dreams, thoughts and feelings – are forms appearing in consciousness. It doesn’t always seem that way. When I see a tree it seems as if I am seeing the tree directly. But science tells us something completely different is happening.

Light entering the eye triggers chemical reactions in the retina, these produce electro-chemical impulses which travel along nerve fibers to the brain. The brain analyses the data it receives, and then creates its own picture of what is out there. I then have the experience of seeing a tree. But what I am actually experiencing is not the tree itself, only the image that appears in the mind. This is true of everything I experience. Everything we know, perceive, and imagine, every color, sound, sensation, every thought and every feeling, is a form appearing in the mind. It is all an in-forming of consciousness.

Phenomenon
The idea that we never experience the physical world directly has intrigued many philosophers. Most notable was the eighteenth-century German philosopher Immanual Kant, who drew a clear distinction between the form appearing in the mind – what he called the phenomenon (a Greek word meaning “that which appears to be”) – and the world that gives rise to this perception, which he called the noumenon (meaning “that which is apprehended”). All we know, Kant insisted, is the phenomenon. The noumenon, the “thing-in-itself,” remains forever beyond our knowing.

Unlike some of his predecessors, Kant was not suggesting that this reality is the only reality. Irish theologian Bishop Berkeley had likewise argued that we know only our perceptions. He then concluded that nothing exists apart from our perceptions, which forced him into the difficult position of having to explain what happened to the world when no one was perceiving it. Kant held that there is an underlying reality, but we never know it directly. All we can ever know of it is the form that appears in the mind – our mental model of what is “out there”.

Delusion
It is sometimes said that our model of reality is an illusion, but that is misleading. It may all be an appearance in the mind, but it is nonetheless real – the only reality we ever know. The illusion comes when we confuse the reality we experience with the physical reality, the thing-in-itself. The Vedantic philosophers of ancient India spoke of this confusion as maya. Often translated as “illusion” (a false perception of the world), maya is better interpreted as “delusion” (a false belief about the world). We suffer a delusion when we believe the images in our minds are the external world. We deceive ourselves when we think that the tree we see is the tree itself.

The tree itself is a physical object, constructed from physical matter – molecules, atoms, sub-atomic particles. But from what is the image in the mind constructed? Clearly it is not constructed from physical matter. A perceptual image is composed of the same “stuff” as our dreams, thoughts, and feelings, and we would not say that these are created from physical atoms or molecules. (There might or might not be a corresponding physical activity in the brain, but what I am concerned with here is the substance of the image itself.) So what is the mental substance from which all our experiences are formed?

Mindstuff
The English language does not have a good word for this mental essence. In Sanskrit, the word chitta, often translated as consciousness, carries the meaning of mental substance, and is sometimes translated as “mindstuff”. It is that which takes on the mental forms of images, sounds, sensations, thoughts, and feelings. They are made of “mindstuff” rather than “matterstuff”.

Mindstuff, or chitta, has the potential to take on the form of every possible experience – everything that I, or anyone else, could possibly experience in life; every experience of every being, on this planet, or any other sentient being, anywhere in the cosmos. In this respect consciousness has infinite potential. In the words of Maharishi Mahesh Yogi, “Consciousness is the field of all possibilities”.

The Projector
This aspect of consciousness can be likened to the light from a film projector. The projector shines light onto a screen, modifying the light so as to produce one of an infinity of possible images. These images are like the perceptions, sensations, dreams, memories, thoughts, and feelings that we experience – the forms arising in consciousness. The light itself, without which no images would be possible, corresponds to this ability of consciousness to take on form.

We know all the images on a movie screen are composed of light, but we are not usually aware of the light itself; our attention is caught up in the images that appear and the stories they tell. In much the same way, we know we are conscious, but we are usually aware only of the many different perceptions, thoughts, and feelings that appear in the mind. We are seldom aware of consciousness itself.